Decolorizing and fractionating sugar cane wax



Patented Apr. 17, 1951 DECOLORIZ ING AND FRACTIONATIN G SUGAR OANEWAX Arthur 'W..Hixson, Leonia, N. J., and Ralph Miller, New York, N. Y., assignors to The Chemical- Foundation, 'Incorpo her-ship corporation No Drawing. Application April 29,

Serial No. 744,796

11 Claims. 1

This invention relates to an improved process of decolorizing and fractionating sugar cane wax.

As is known, the surface of sugar cane stalks is covered by a thin layer of wax. In addition, like most plants, sugar cane contains a small quantity of various organic compounds such as fats, sterols, chlorophyll, carotenoids, hydrocarbons, long chain alcohols and the like. When sugar cane is pressed, preliminary to obtaining sugar, an appreciable percentage of these organic compounds are dispersed in the crude juice. The .crude juice is clarified by the addition of lime or lime and a phosphate compound. The resulting precipitate drags down either mechanically or by adsorption nearly all of these ma-, terials plus any solids in the juice including those that may be deliberately added as filter aids. Clarified juice .is separated from the precipitate by filtration. The filter cake is termed the clarification mud press cake or more simply the mud press cake. In most instances the mud press cake is discarded as a waste product although it frequently is employed as a fertilizer.

Much work has been done on the recovery of additional values from mud press cakes but no commercially accepted method has been found to date. Perhaps the most comprehensive work which has been carried out in this field is that of the U. S. Department of Agriculture as ,described by R. T. Balch inJContributions #22 and #72 of the Agricultural Chemical Research Di.- vision and in The Sugar Bulletin, pp. 106-9, 117-9, 123-7 (April 15, May 1 and 15) 1944. This work has been summarized, confirmed and extended by C. F. Bonilla in the publication, Sugar, p. 36, April, 1945.

As reported by these investigators and others the potentially useful compounds such as the fats, waxes and sterols contained in the mud press cake can be recovered as a crude dark mixture by extracting the mud press cake, preferably after drying it, with an organic solvent such as toluene, petroleum naphtha, carbon tetrachloride, isopropyl acetate, ethylene dichloride and the like. The extracted material is a wax-like substance which is greenish brown in color, tacky to the touch, melts at about 50 C. and sometimes possesses a grassy odor. It contains asubstantial percentage of fat, various color bodies such as chlorophyll and chlorophyll decomposition or polymerization products and a hard, high melting point wax. The method which Balch regards as practical. for the economical treatment of this mixture of potentially useful substances is described in U. S. Patent No. 2,381,420.

rated, a New York mem- A primary object of this invention is to effectively and economically remove color bodies from sugar cane wax.

Another object is to economically produce from crude sugar cane wax a light colored fraction composed primarily .of fat and fatty acids and-a light colored fraction of a substantially fat-free wax. Each ,of the fractions may be further refined by known methods if necessary or desirable but these additional steps do not constitute any part of this invention.

A further object of this invention is to permit crude waxes, irrespective of their variation in composition, to be processed effectively, and with minor changes, if any, in procedure.

An additional important object of this invention is to fractionate crude sugar cane wax continuously.

Additional advantages of this invention will be apparent from the subsequent description.

It is apparent from the described method by which crude sugar cane wax is produced and it is known from the prior art that the composition of crude sugar cane wax will vary with the variety of the cane from which it was derived, the clarification procedure employed, the conditions to which the mud was subjected, and the solvent employed to extract the wax from the press cake.

A readily saleable and technically valuable product'canbe obtained if most of the color bodies of the crudewaxcan be segregated into a relatively minor fraction in an economic manner. 8

We have discovered that most of the color bodies in .crude sugarcane wax can be substantially concentra'ted .by treatment with liquefied, normally gaseous, parafiinic hydrocarbons such as propane, butane or mixtures of ethane, propane andthe butanes with similar solvent characteristics ac; cording to the proceduredescribed below. In addition to using propane to segregate the color bodies, thesame solventv can be employed to separate the low melting soft fats and fatty acids from the high melting point, hard, wax. Thus, thesame solvent hasca multiplicity of uses as well as being readily availableand easily recoverable;

In a preferred procedure the crude waxwhich, as described, is the crude solvent extract from mud press cake, is melted and continuously pumped into a. liquid-liquid extraction tower close to its top. The liquified hydrocarbon or mixture of liquefied hydrocarbons is" continuously pumped into the tower close to the bottom. :B-y maintaining. thewcontent ,of the tower at asuit,- able temperature .or within a suitable temperature range, and the ratio of solvent to wax at a suitable figure, or within a suitable range of ratios, it is possible to keep two immiscible liquid phases within the tower. The hydrocarbon solvent phase possesses a density lower than the crude wax phase and therefore rises and flows out of the tower at its top. The crude wax phase settles and leaves the tower at the bottom. The

two phases are intimately contacted as they pass,

each other countercurrently. The constituents of the crude wax soluble in thesolvent phase under the conditions that exist within the tower are transferred from the crud wax phase to the upfiowing solvent phase and leaves the tower at the top. The crude wax phase contains those constituents of the crude wax insoluble in the hydrocarbons solvent under the, conditions existing within the extraction tower plus the balance of the hydrocarbon solvent.

We have found that when the hydrocarbon solvent is propane or a mixture of hydrocarbons possessing similar solvent characteristics a ratio of about or more parts by weight of solvent to wax is suitable depending upon the tempera ture; By proper control of the temperature and solvent ratio, it is possible to have about 95% of the constituents of the wax soluble in the solvent leave the tower in the solvent phase while the remainder of the soluble constituents of the wax, the non-soluble components, substantially all the color bodies, and approximately an equal volume of the solvent leave the tower at its base. Each stream leaving the tower flows to a solvent recovery unit in which the solvent is separated, recovered and recycled to the extraction step.

The pressure existing within the extraction tower must be suificiently high to maintain the particular used solvent in the liquid phase. Usual y. the pressure within the tower is equal to the vapor pressure of the solvent at the temperature at which it is maintained in the tower plus a superimposed pressure of about 30 pounds.

Should this solvent be recovered from each stream without any further treatment or manipulation the crude wax would be divided into two parts or fractions composed respectively of a minor fraction of the crude wax in which the color bodies are concentrated and a major fraction containing the remainder of the charge material. This treatment is sufiicient for those uses of the wax which simply require a lighter colored wax but do not require a wax of maximum hardness and melting point.

' We have found that not only can thecolor bodies of crude sugar cane wax be concentrated by means of a liquefied, normally gaseous hydrocarbon in the manner described above but the same solvent can be used to separate the low melting point fats from the high melting point wax. Instead of immediately recovering the solvent from the stream which emerges from the top of the decolorizing tower, it is only necessary to reduce the temperature of the liquefied hydrocarbon solution to cause a large proportion of the high melting point wax to come out of solution as a solid while maintaining the fat in solution. 0bviously, the proper temperature to which the liquefied hydrocarbon solution should be chilled will .depend upon the ratio of solvent to solute in the solution and the ratio of high melting point wax to fat. The solid wax is separated from the solution by filtration, settling, centrifuging or any other convenient means. It has also been found that substantially all the color bodies which were not removed in the initial decolorizing step stay in solution when'the wax comes out of solution.

4. The solvent is readily removed and recovered from the dissolved fat. Obviously, the fat fraction contains practically all the color bodies not removed in the initial decolorizing step. Usually the color of the recovered fat is sufficiently light for most purposes. It will rarely rade lower than 6 on the Gardner-Holdt scale.

In carrying out the color fractionation step in the extraction tower a suitable temperature at the top outlet is about 180 F. when propane is the solvent. A lower temperature should prevail in the lower section of the tower. A suitable ratio ofsolvent to crude wax under these conditions is about to l by weight.

When separatin the relatively low melting fat from the high melting wax by means of propane,

the temperature may be maintained within the approximate range of 50 to 100 F. and still obtain good results. At lower temperature, some of the higher melting point fat may crystallize from solution especially if the ratio of solvent to 'fat is too low. At substantially higher temperatures, the yield of wax will be diminished.

Because the process described herein is simple and economical it represents an important advance in a field that could not recover and refine products which it has been discarding for many years although aware that potentially valuable products were being thrown away.

While a specific of decolorizing and fractionating sugar cane wax, utilizing propane as a selected solvent, has been described, it will be understood that this is given to exemplify the broad concept of utilizing liquefied, normally gaseous paraffinic hydrocarbons at elevated temperatures to eifect decolorizing of the crude wax and optionally to then fractionate the preliminarily decolorized wax into a high melting wax fraction anda fraction concentrated in the original fatty materials.

We claim: a

1. The method of fractionating crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable fractions therefrom which comprises, contacting melted crude wax with liquid propane at a temperature of about F. and a pressure sufficiently high to maintain the propane in liquid phase to form two, separable immiscible liquid phases of different densities, separating the phases and recovering the fatty materials and wax from the less dense phase.

2. The method of fractionatin crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable products therefrom which comprises, contacting melted crude wax with liquid propane in a continuous liquid-liquid extraction system at a temperature of about 180 F. and a pressure sulficiently high to maintain the propane in the liquid phase to form two, separable immiscible liquid phases f different densities, in the more dense phase of which the color bodies are largely concentrated and in the less dense phase of which the fatty materials and wax are largely concentrated, separating the phases and recovering the fatty materials and wax from the less dense phase.

. 3. The method :of fractionating crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable products therefrom which comprises, contacting melted crude wax with liquid propane in a continuous liquid-liquid extraction system at a temperature of about 180 F. and a pressure ,sufficiently high to maintain the propane in the liquid phase to thereby form two immiscible liquid phases of different densities, in the less dense phase of which the fatty materials and wax are largely concentrated and in the denser phase of which the color bodies are largely concentrated, continuously separating the less dense phase from the more dense phase, reducing the temperature of the less dense phase to a degree sufficient to insure cry tallization of substantial quantities of the contained wax while retaining the fatty materials in solution in the solvent and then separating the wax from the solution.

4. The method of fractionating crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable products therefrom which comprises, contacting melted crude wax with liquid propane in a continuous liquid-liquid extraction system at a temperature of about 180 F. and a pressure suificiently high to maintain the propane in the liquid phase to thereby form two immiscible liquid phases of different densities, in the less dense phase of which the fatty materials and wax are largely concentrated and in the denser phase of which the color bodies are largely concentrated, continuously separating the phases,

reducing the temperature of the less dense phase to between 50 F. to 100 F. to thereby largely crystallize the wax and separating the crystallized wax from the solution.

5. A process of treating crude sugar cane wax containing color bodies, fatty materials and wax to recover a valuable lighter colored wax-containing fraction which comprises, passing melted wax to the upper section of a continuous counter-current elongated extraction zone, passing liquid propane into the lower section of the zone, while maintaining a temperature of substantially 180 F. within the zone, continuously withdrawing from the lower section of the zone a liquid fraction containing some propane and a preponderant amount of the color bodies of the charged crude wax, continuously Withdrawing from the upper portion of the zone a liquid fraction consisting of propane and substantially all of the fatty materials and wax of the crude charge and recovering such fatty material and wax from the propane.

6. The process of fractionating crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable products therefrom which comprises contacting the crude wax in a continuous counter-current extraction system with a liquified, normally gaseous parafiinic hydrocarbon; the ratio of liquified hydrocarbon to wax and the contacting temperature being selected so that two liquid phases differing in density are present; said temperature being that superatmospheric temperature at which two liquid phases are present at the selected ratio; continuously separatin the less dense phase which contains the bulk of the fatty materials and wax from the more dense phase which contains the remainder of the fatty material and wax and substantially all of the color bodies and recovering the fatty materials and 'wax from the less dense phase.

'7. The process of fractionating crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable products therefrom which comprises contacting the crude wax with a liquefied, normally gaseous paraffinic hy- 6 drocarbon; the ratio of liquefied hydrocarbon to wax and the contacting temperature being selected so that two liquid phases differing in density are present; said temperature being that superatmospheric temperature at which two liquid phases are present at the selected ratio; separating the less dense phase which contains the bulk of the solvent, fatty materials and wax from the more dense phase which contains the remainder of the solvent, fatty material and wax and substantially all of the color bodies and reducing the temperature of the separated less dense phase; the reduced temperature of the separated less dense phase being higher than the temperature at which any appreciable amount of the fatty material is in the solid phase and below the temperature at which the solvent can maintain all the Wax in solution thereby forming a solid wax phase; separating the solid wax phase from the liquid phase and recovering the wax from the separated solid wax phase.

8. The process of fractionating crude sugar cane wax containing color bodies, fatty materials and wax to recover valuable products therefrom which comprises contacting the crude wax in a continuous counter-current extraction system with a liquified, normally gaseous parafiinic hydrocarbon; the ratio of liquefied hydrocarbon to wax and the contacting temperature being selected so that two liquid phases differing in density are present; said temperature being that superatmospheric temperature at which two liquid phases are present at the selected ratio; continuously separating the less dense phase which contains the bulk of the fatty materials and wax from the more dense phase which contains the remainder of the fatty material and wax and substantially all of the color bodies and reducing the temperature of the separated less dense phase; the reduced temperature of the separated less dense phase being higher than the temperature at which any appreciable amount of the fatty material is in the solid phase and below the temperature at which the solvent can maintain all the wax in solution thereby forming a solid wax phase; separating the solid wax phase from the liquid phase and recovering the wax from the separated solid wax phase.

9. The process of claim 6 in which propane is the liquefied, normally gaseous paraffinic hydrocarbon.

10. The process of claim 7 in which propane is the liquefied, normally gaseous paraflinic hydrocarbon.

11. The process of claim 8 in which propane is the liquefied, normally gaseous parafiinic hydrocarbon.

AR'II-IUR W. I-HXSON. RALPH MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,118,454 Schaafsma May 24, 1938 2,270,674 Pilat et a1 Jan. 20, 1942 2,281,865 Van Dijck May 5, 1942 2,381,420 Balch Aug. 7, 1945 2,432,021 Larner Dec. 2, 1947 

1. THE METHOD OF FRACTIONATING CRUDE SUGAR CANE WAX CONTAINING COLOR BODIES, FATTY MATERIALS AND WAX TO RECOVER VALUABLE FRACTIONS THEREFROM WHICH COMPRISES, CONTACTING MELTED CRUDE WAX WITH LIQUID PROPANE AT A TEMPERATURE OF ABOUT 180* F. AND A PRESSURE SUFICIENTLY HIGH TO MAINTAIN THE PROPANE IN LIQUID PHASE TO FORM TWO, SEPARABLE IMMISCIBLE LIQUID PHASES OF DIFFERENT DENSITIES, SEPARATING THE PHASES AND RECOVERING THE FATTY MATERIALS AND WAX FROM THE LESS DENSE PHASE. 